Beater wheel mill



April 15, 195s B. REICH BEATER WHEEL MILL Filed June 5J 1956 INVENTORv .A

BEATER WHEEL MILL Bruno Reich, Stuttgart-Weilimdorf, Germany, assignor to Kohlenscheidungs-Gesellschaft, m. b. H., a corporation of West Germany Application .lune 5, 1956, Serial No. 589,481

3 Claims. (Cl. 241188) The invention relates to a beater wheel mill having an `axial inlet for receiving the carrier gas and the raw material to be ground therein, and being provided with means for passing the material and carrier gas through the beater Wheel in radial directions. More specifically the invention relates to a beater wheel mill having lateral bars connecting the Wheel disc of the beater wheel with the ring disc spaced therefrom and in which these bars are lined with heavy liner plates.

In beater Wheel mills as presently known and in Which the beater plates or liner plates possess the shape of a parallelepiped, unusual heavy demands as to abrasion `are made on the material inflow portion of the beater plates, that portion which is facing the axis of the wheel, whereas the material outflow portion is subjected to relatively light demand of Wear. This results in a wearing through of the inflow portion of the beater plates while at the same time the outflow portion retains nearly the same thickness as the original thickness of the plates. The extensive Wear of the inflow portion of the beater plates necessitates early replacement thereof since a continuation of operation of the mill would otherwise lead to abrasion of the beater -bars which must be prevented at yall costs. Accordingly only approximately 50% of the weight of the beater plates can be made use of before replacement thereof must be considered. This results in high abrasion costs and considerable reduction of the operating availability of the mill.

In accordance with the invention a considerable improvement of these conditions is secured by reducing the thickness f the beater or liner plates in the direction of material iiow. In this connection the thickness of the liner plates can, in accordance with the invention, be either reduced by following the line of a gradual slope or by steps. In this way it is possible to operate the beater wheel continuously for a longer time per pound of liner plate since up to 80% of the Weight of the plates can now be made use of. Accordingly not only the availability rate of the mill, i. e. operating time per pound of liner plate replaced, is thereby considerably i11- creased but operation costs due to abrasion are also substantially reduced.

In accordance with the invention the operating costs due to Wear are further diminished by sub-dividing the beater plates into several portions along planes parallel to the wheel axis. In this manner those beater plate portions which are located near the Wheel axis and which have not been completely used up can be utilized as liner plates at locations more distant from the axis of the beater Wheel. In addition the total weight of the individual -beater plate is distributed over several beater plate sections so that these beater plates can vbe handled easier when replacement becomes necessary.

Furthermore the invention provides that the beater plates are bent near the end facing the Wheel axis in a direction opposing the direction of rotation. In this manner a shock free entrance of the material and carrier gas into the beater wheel is eiected whereby additional abra- StateslPater-it f' sion of the inow side portion of the beater plates due to turbulence is substantially reduced.

Further details and objects of the invention will becomeapparent from the drawing and from the following description thereof.

In the drawings-- Fig. l shows an elevational partial section of a beater wheel mill, said section being taken in a plane parallel to the axis of the mill.

Figs. 2, 3 and 4 show parallel sections taken respectively on lines 2--2, 3 3 and 4 4 of Fig. l, illustrating in an enlarged scale beater plates of different forms.

Referring to Fig. l the `beater Wheel mill comprises a beater wheel assembly 16 rotating in a housing 11 and having a solid wheel disc 12, a ring disc 14 and lateral bars 16 connecting wheel dis-c 12 and ring disc 14. Bars 16 are protected by liner plates or beater plates 13 (see Figs. 2, 3 and 4). The beater wheel assembly 1) is supported by a shaft 20 journalled at one end only and driven by an electric motor or the like, not shown. Coal and carrier gas is introduced by way of duct 22 into the entrance chamber 24 of the mill from where the coal and gas enter the beater wheel assembly 10 in an axial direction. The coal and carrier gas thereupon pass through the beater wheel assembly 10 in radial directions while the coal is being ground, and are evacuated through outlet duct 26 to pass into a classifier, not shown. The fines suspended in carrier gas having been separated from the coarser material in the classifier are delivered to a point of use, for instance to the burners of a pulverized coal tiring furnace. The coarse and oversized particles expelled by the classifier are returned for further grinding to the beater wheel 10 by way of duct 28 and mill entrance chamber 24.

The beater wheel assembly 10 is constructed as follows: The Wheel disc 12. and the ring disc 14 are provided with a slot like annular depression 3i) extending around the discs. Side end flanges 32 of connecting bars 16 are adapted to t into these recesses and are secured to the discs 12 and 14 by means of rivets 34. The space left vacant between one beater plate assembly 18 and the flange of the preceeding connecting bar 16 is closed up by a filler piece 36. The iiller piece 36 as Well as another liller piece 39 provided underneath each beater bar assembly 18, are secured by vscrews 38. Into the thus remaining unoccupied space of the slot like annular recess are inserted beater or liner plates 18. These beater plates accordingly are secured on all sides without requiring special shop drilling or other workings for the purpose of providing means for adequate support of these liner plates 18 on the bars 16 or on Wheel disc 12 and ring disc 14.

Although the invention has hereinabove been described in connection with a coal pulverizer the inventive irnprovement can obviously also be applied with equally beneficial results to the pulverizing of material other than coal such as chalk, for instance.

Iclaim: l

l. A beater wheel mill having a beater wheel adapted for axially receiving material and carrier gas and for radially passing said material and carrier gas through the beater Wheel, comprising a wheel disk, a ring disk arranged in laterally spaced relation to said Wheel disk, circumferentially spaced lateral bars connecting said wheel disk and said ring disk, and beater plates protectively lining said connecting bars, said beater plates having a circumferential thickness which is reduced in a radial direction away from the axis of said beater wheel, and said beater plates being subdivided into portions along planes substantially parallel to the Wheel axis.

2. A beater Wheel mill in accordance with claim 1 in which the thickness of said beater plates is reduced in steps.

'Pa-tentes 'Afmvv '15,1958

assegna 3 3. A beater wheel lmill in accordance witlcli'n l in which th beater plates are b ent in a direction opposite to that of wheel rotation and adjacent the ends thereof facing the wheel axis.

References Cited in the le of this patent UNITED STATES PATENTS 1,228,338 Marks May 29, 1912 4 Mik p Dec. 2s, v1937 Schacht Apr. 18, 1939 Kennedy Aug. 13, 1940 Kennedy July 28, 1942 FOREIGN PATENTS Germany June 18, 1954 Germany Nov. 17, 1955 

